History of Computed tomography
Posted on:3/24/2006
| The CT system was invented by Godfrey Newbold Hounsfield in Hayes, England at THORN EMI Central Research Laboratories (which spawned Sensaura, now owned by Creative Technology) using X-rays. |
The CT system was invented by Godfrey Newbold Hounsfield in Hayes, England at THORN EMI Central Research Laboratories (which spawned Sensaura, now owned by Creative Technology) using X-rays. Hounsfield conceived the idea in 1967, and it was publicly announced in 1972. Allan McLeod Cormack of Tufts University independently invented the same process and they shared a Nobel Prize in medicine in 1979. The original 1971 prototype took 160 parallel readings through 180 angles, each 1° apart, with each scan taking a little over five minutes. The images from these scans took 2.5 hours to be processed by algebraic reconstruction techniques on a large computer.
The first commercial CT machine using X-rays (called the EMI-Scanner) was limited to making tomographic sections of the brain, but acquired the image data in about 4 minutes (scanning two adjacent slices) and the computation time (using a Data General Nova minicomputer) was about 7 minutes per picture. This scanner required the use of a water-filled Perspex tank with a pre-shaped rubber "head-cap" at the front, which enclosed the patient's head. The water-tank was used to reduce the dynamic range of the radiation reaching the detectors (between scanning outside the head compared with scanning through the bone of the skull). The images were relatively low resolution, being composed of a matrix of only 80 x 80 pixels. The first EMI-Scanner was installed in Atkinson Morley's Hospital in Wimbledon, England, and the first patient brain-scan was made with it in 1972. In the US, the machine sold for about $390,000, with the first installations being at the Mayo Clinic and Massachusetts General Hospital in 1973.
The first CT system that could make images of any part of the body, and did not require the "water tank" was the ACTA scanner designed by Robert S. Ledley, DDS at Georgetown University.
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